Telegraph regenerating system



Dec. 27, 1938.' M H. wooDwARD TELEGRAPH REGENERATING SYSTEM Filed July l, 1936 ATTORNEY Patented Dec. 27, 1938 UNIT-ED `STATES TELEGRA'PH REGENERATING-'SYSTEM MarionH. Woodward, Arlington, Va., assignor, by mesne assignments, to International YStandard Electric Corporation, New York, .N. Y., .a corporation of Delaware Application luly 1, 1936, Serial No. 88,367

4 Claims.

The present invention'relates to an vimproved regenerator circuitlor re-shaping telegraph signals which are received from an incoming line with a certain amount of distortion, and repeating vthem to an outgoing line without distortion.

More specifically this invention provides a reshaping .regenerating circuit for use with signals which aretransmitted vat a substantially constant rate,'as`from a tape transmitter or other constant speed transmitting device.

'One of the principal features of this invention is the provision of an improved timing circuit 'for controlling the regenerating relays, Ythis timing circuit 'comprising `a self-energized tuning 'fork and a speed correcting circuit for maintaining the tuning 'fork in synchronism with the `fundamentalrate of signal transmission, generally referred 'to as the center-hole speed.

It should be understood that in signal regenerating circuits used with signals of constant center-hole speed, it is `usualtoprovide a timing arrangement adapted to operate substantially 'in synchronism with the center-hole speed of the received incoming signals and then to arrange the signal yrepeating or'regenerating relays which retransmit the signal ytothe outgoing line so :that they are controlled jointly by this timing mechanism and yby the distorted'incoming signals. The difficulty in theusual arrangements o'f 'this type has been to provide `such a timing mechanism which 'will remain 'sufciently accurately in `synchronism with Vthe average center-hole speed of theincoming signals and yet have vsuch a uniformity 'of vspeed Vthat the time Ypulses generated `by it will not instantaneouslyyary in'speedwith the accidental variations of individual signal pulses. Y

lAccording to the present invention a timing mechanism having the desired characteristics is provided, which has "for its principal Velement a j self-driven tuning fork. This self-driventuning which shall yet be comparatively unaiected by the lindividual distortions of the `signal pulses, especially with regard to that vform of distortion generally known as characteristic distortion.l Another primary object of the'present invention is to provide such a 'fork correcting circuit which shall be adapted to readily 'cooperate 'with the 4type of vautomatic bias 'corrector described in UnitedStates vPatent 1,929,879 to A. F. Connery.

More specifically it .is `an `object of .this'invention -to provide a tuning fork `timing :device Iin which each correction performed rby the fork corrector equipmentlshall alter the kphase 'of the fork by a 'xed predetermined amount iin a fixed predetermined direction, the number 4of correci' tions occurring per minute'bein'g varablelinac'- cordance with the difference between the'n'a'tural fork speed and the average center-holeispee'd of the incoming signals.

This invention is applicable to vrsignals of f'the well known Baudet type and of the so-calledsubmarine Morse type, as well as to "other types v'o'f signals, provided only that these signals arecharacterized by some repeatedly recurring 'characteristic and are transmitted at la vsubstantially constant speed. The speccembodiment'inconnection with which this invention is'here rdescribed is adapted tol voperate with the so-'called submarine Morse type of telegraphic `signals lin which three different types of impulses (positive, negative and zero) are employed,:all pulses'being of equal length.

The invention may best be understood byireferenceto the accompanyingsingle figure-:of kdraw-'- ings which represents a regenerating Arepeater 'for reshaping and yretransmitting.submarine Morse signals, this repeater having l'a fork-controlled timer -in accordance with `Vthe invention. "It'wvill be observed lthat in "this vdrawingt'hereare rshown a number of polarized relays veach having two-or more windings. For simplicity in rreading 'the drawing these windings have `been fso `arranged that in every case a 'current whose fconventional direction of `flow-is fromrightto left throughfany o'f the windings Awill Avtend to move thefcontact tongue of its relay from right to left. :Similarly a current flowing lfrom left'to rightit'hrough 'any winding of any polarized `relay in the "drawing will tend to vmove the associate'd'relay tongue-from left to right.

The invention may be best "understood (by reference to the accompanying single'iigure'of -drawings which represents a regenerative repeateri'for submarine Morse 'signals having va 'fork controlled timer in accordance with 'the present invention.

Referring now to the drawing, AI representsth'e incoming signal cable and 2 is a `polarizedicable receiving relay of the moving `coil type. ,'.It :is assumed that this relay will `lbe actuated by .the

. incoming signals in the usual imanner, the signals originally coming from an 'automatic cable vtransmission in the usual form. When afdot signal is received :the tongue o'f Arelay 2 will make with its clot contact whereas a dash signal cause it to make with `its dash contact. Azeroior i i relay 2. Under control of these last named relays 3 and 4 the transmittingrrelays 5 and 6 are operated to Vtransmit to the outgoing cable 'I regenerated signals corresponding to the distorted signals received in cable I. pal chain of apparatusrforr regenerating signals between cables I Vand I consists of relay 2, relays 3 and 4 and finally relays 5 and 6 in the order named. Y

In order to eliminate the distortion in thesignals the operation of the transmitting relays 5 and 6 is controlled not only by the chain of regeneratingapparatus above described but also jointly by the special timing equipment which is a particular feature of the present invention. This timing equipment is shown-inside of the dot and dash rectangleV in the drawing and its exact action will be fully explained below. Briefly, however, the Vfunction of thisV timingV equipment is to intermittently connect ground to wire 8 synchronism with the average center-hole speed of the incoming signals. It will be noted that the circuits through transmitting relays 5 and 6, although theyV are prepared by the operation of relays 3 and 4 under control of the moving coil cable relay 2 are notfcompleted until ground is connected to wire V8 by the timing device. The result of this arrangement is that the transmitting relays 5 and 6 will remain in the position previously taken until the instant when the timing device places the pulse of ground on wire 8. Then at this instant the transmitting relays will shift to the new positions determined by the positions occupied at that time by the locking relays ,3 and 4.

Referring more particularly to the Vtiming ar-V` rangement, relay 9 is a corrector relay adapted to be .operated by either of two windings I0 and II, which are connected in series with the locking relays 3'and 4. This relay 9 is preferably of the two-position polarized type for the sake of speed andsensitivity and is electrically biased by an auxiliary winding I2 so that in the absence of current through its operating windings it will return to its spacing contactY S as shown in the figure. The tongue of relay il` is connected to positive battery through condenser I3 so that upon motion of this tongue against Vits marking Contact M a momentary surge of charging currentfwilly ow throughthe condenser and the relay contacts, thence through one or more windings of relay I 4,y through the tongue of relay I5 Vto ground. Resistor I8 is connected to theV normal or spacing contact of the corrector relay 9 to discharge condenser I3 each time this relay returns to normal so as to prepare for another surge of charging current upon the next operation of this relay. It will be noted that .if relay I5 is in its Ynormal position with its tongue resting against .its spacing contact the path for the above mentioned charging current extends through both windings IB and I'I of relay I4. These windings are so balanced that in this case relay I4 will not tend to operate. If, however, relay I5 ris in its energized position with its tongue resting against its marking Contact M,.the path for said charging current extends only through winding I6 so that in` this condition the charging current will energize the auxiliary correction relay I4. This auxiliary corrector relay is also of the two-position polarized type and is electrically biased by means of winding 3'I so that its tongue normally rests against its spacing contact. Y

' The principal stabilizingV element of the timing mechanism consists` of fork I itself-driven byV Thus the princi- *n magnet 20 through back contact 2|. This fork is normally adjusted to vibrate at a rate slightly faster Vthan the average center-hole speed of the incoming signals. CooperatingV with this fork is contact 23 which serves to control the operation of relay I5 through condenser 24 iri shunt with of relay I5, resistor 25 and condenser 24, the Y tongue of relay I5 is caused to close against its marking contact once f or each cycle o f the fork, the duration of these closures and their phase relative'to the fork cycle being adjustable within certain limits.

It should now be seen Ythat the equipment thus far described in the timing mechanism is in general vbased upon two independently actuated mechanisms (tuning fork I9 and corrector relay 9) one Vof which has a natural period determined by the mechanical characteristics of the fork and the other of which is controlled from the incoming signal. Jointly under the control of these two mechanisms is'auxiliary corrector-relay I4 which, as above described, is adapted to operate upon the energization of relay 9 only if suchenergization coincides with aclosure of the marking contact of the fork-controlled relay I5.

Under control of this auxiliary corrector relay I4 there are provided correcting circuitsY and equipment for delaying-.the phase of the tuning fork asfollows; Correcting relay 26 is connected tothe marking contact of relay I 4v so as'to be energized by the operation of the latter. Also connected to this same marking Contact is locking winding 21 of the relay I 4 itself in series'with a resistor 28. Slow release relay 29, on the other hand, is connected to the normal or spacing contact ofrelay I4. Thus, upon the energization of relay I4 correcting relay 26 will be operated. relay I 4Vitself will be locked and slow release relay 29 will commence to deenergize. This in turn will then cause the release oi relay I4 and then of relay 26, while relay 29 will be reenergized in preparation for another release. Thus. it will be seen that upon each energization of relay I4 correcting relay 25 will become actuated and will remain in its actuated position for a xed predetermined time. The marking Contact of'relay 26 is connected so as to apply ground potential through a variable resistor 3D directly to the driving magnet 2Il of fork I9. Since the circuit for this ground potental'is independent of the back contact 2i nf the fork. the result of the operation of relay 2S will beto superpose upon the intermittent driv- VingV current through Ymagnet 29 acontinuous current of adjustable value. Because of the characteristics of the Vfork and the normal amplitude at which it is operated the result of such a oontinuous energization will be not'only to decrease the amplitude of the fork slightly but also Vto slow releasing byadjustment of its armature tensions aanname andi-travel, aas ..well :as-by varyingitheA volumegand Shape of the "well known :eddy lcurrent sleeves which aretprovided in, relays Lof 'this type.

vTheaabove 'description of apparatus and their circuit Irelationships when itaken together with the drawingshould .almostsufceito make clear how the vequipment a operates. For completeness, however, the following general ldescription ,of the method E'of operation willbefgiven.

.It 'will be assumed that distorte-d fsignals vare being received over `,cable by K4moving acoil relay 2 :andiitfwill'be Aassumed'tllat fork I9 .is vibrating substantially Yin synchronism lwithi'he average center hole speed of these xsignals, the closuresiof contact -22 occurringroughly at the same time as-the *centerfof eachsignal element. The fork I9, however, 'is vibrating slightly more .rapidly 'than the center hole speed of the incoming signals sothat over a period of time the phase of fthe forkis gradually advancing with respect to the signal. Under control of the contacts of themoving coil relay 2, corrector relay 9 is intermittently operated, this relay 9 operating upon veach -.c1osure of the dash or dot contact .of relay 2. fIt should vbe noted that the correctorrelay will not operate vinresponse to each element of the received signal but only in response to certain ones .of these elements since a 4zero or no current pulse will never actuate the corrector relay, .and-sincaadash or .dot pulse precededby a similar pulse .will not ."actuate this v.relay but AmerelysholdA it operative.

[f, 'foriexample ltheincoming `signal consists of theimessage ONDX (which would be represented bythe :elements (1-),minus1(2) minus (3) minus '(4),'.zero-(5) @minus (6);plus (7) zero (8) .zero (9) zero (10) `minus (11) .plus (.12) plus (13) zero (14) minus y(15) 4plus 1(16) .plus v(1'7) minus) relay '.9 @would :be actuated only by the first, fifth, sixth, tenth, 'eleventh7 fourteenth, fifteenth `and seventeenth pulses. Therelay will, of course, remain operated :during the second, third, twelfth landfsixteenth rpulsesrbut will not reoperate ,upon

lthese pulses. Because of the fact vthat condenser I3 charges*almostimmediately after the tongue of :relay 9 strikes Tits, marking contactthe continued energization of vthis relay 9 willbe ineffective and current will flow rthrough the windings of relayflll `only whenrelay 9"moveslfrorn'its unoperatedstate toitsoperated state.

At -the same time that corrector -relay 9 is intermittently Aoperating .un-der the `control ofthe signal as above described, relay l5 is beingregularly operated undercontrol ofthe fork'contact 23. The adjustment of this relay I5--and of the lresistor and condenser -24 and 25 which determine its operating characteristics vare such that Vrelay l'will not operatevuntil afterthe tongue of relay 9 has closed .against its marking contact and. condenser .1.3 -has -substantially finished charging. This statementis vof coursebased on the assumption'vthat the fork happens now to be. in synchrof nism with the signal so that Vthe'closureof ,con- Vtacts 22 rand 23 takes'place approximatelyiduring the center of a signal pulse. Under these conditions-therefore, .relay I4 will .not'become energized `and no correction will be applied to the lfork.

`As the fork gradually advances in phase, however, with respect to the signal it will finally occur that the tongue of relay I5 closes against its marking contact before thelcharging, of condenser `I3 'is finished. rIn this case relay lll will be energized through its winding I6 and will immediately lock itself through its Winding 2l and also :energize correcting .relay 12.6 tofslow 'down'.'the vibrations "of vthe fork. .The Vcorrection.aapplieclto the fork vby relay .26`will continue for a 'certain length'of time determinedby the lcharacteristics of slow release relay29 `and .will nally :be *terminated whenxthe :dropping v,of this 'slow release relay `unlocks relay t4 (by short circuiting vits winding :2 '1) which thenz .releaseszrelayg26.

It Will'fbe vnotedthat the above -described Ycorrecting action will take place at therst'opportunity'each time vthefork has advancedinphase with `respect to :the signalby more than a tolerated amount. 'The opportunities for Vcorrection will not occur at every signal pulse since relay "9, as above described, f will become actuated only f at certain: points in the ,-signal. 'In the case of the message above chosen, for example, the only points at which correction could Ypossibly take place would be on the rst,'fth, sixth, tenth,

eleventh, fourteenth, fifteenth and seventeenth signal elements. `But in-all normal messagesopportunities for correction: will occur .more than sufficiently often to maintain a satisfactorysynchronism.

-Oneof the limportant advantages 'of this :cor-

recting system is that it is always controlled by-a certain lpart of Ithe signal pulse, namely, `the-.beginningcf the pulse. Another very 'important feature is that this control is forthe-most part eiected by those signal pulses which are =unusu r ally Iretarded with-respect to theaverage centerhole phase of the signals.

It is Well known that as a result of the characteristics o-f long lines a positive-pulse which immediately follows a negative pulse or a negative pulse which immediately follows a positive pulse is =more retarded during. transmission vthan the average signal element. In the case ofthe particular message `above chosen for illustration,

such pulses as sixth, eleventh, fifteenth iand,

seventeenth, for example, will be markedly late in arriving. On the other hand, such a pulse as the fifth one will be slightly rearly; such `a pulse as the fourteenth one will be slightly late;

anda pulse such as the first or tenth will besubstantially normal.

Under ordinary operating conditionsnsince `the fork advances in Yphase only very slowly with respect .to the signal thecorrections will be nearly all controlled by the late pulses, such as the sixth, eleventh, fteenth and seventeenth. This fact is of great value in reducing the drift of fork phase with respect to signal phase and vis also of primary importance in making the system adaptable for use with the bias corrector described in United .States Patent 1,929,879. Furthermore, it is a very great advantage of the present'invention that the corrections appliedto the fork are always of a flxed strength and endure for ra fixed time, thus, resulting 1in setting back the phase of the fork by an amount .which is independent .of the .instantaneous -distortion of the signal used for correction.

The operation of the actual signal regenerating or repeatingrelays 3,4, 5 and 6 is very'nearly self-explanatory and need only briefly ybe outlined.

YUpon Vthe reception of a dash or dot the corresponding relay 3 or A4 is energized in an obvious manner. Such operation `preparesoperating circuits r'for the corresponding transmitting relays 5 ands. Atabout the time corresponding tothe center of the lreceived'signal pulse (or va short time thereafter to allow for relay operations) when it can be assumed that the correct locking relay has been operated,ccontact 22 of fork I9 closes. This closure completes the circuit prepared by the locking relay so as to Vcause the transmitting relays at this moment to take up positions corresponding Vto the locking relays which control them. With respect to the outgoing cable this Inoment is the start of a new pulse. During the periodV that contact 22 is closed the Vlocking relays are prevented from altering their position by windings 32, 33, 34 and 35, the appropriate ones of which are at this time connected in series with the transmitting relays and with the fork contact 22. When the tongue of relay 2 leaves its dot or dash Contact, or upon the opening of contact 22 (whicheverY is later) the locking relays 3 and 4 will return to normal; but the transmitting relays will remain in the position in which they have been set until the next closure of fork contact 22.

It will thus be seen that the pulses sent out over the outgoing cable are governed in character by the centerY portions of the incoming pulses, which portions of course VareV the least likely to be erroneous. The timing, however, of these outgoing signals will be wholly controlled by contact 22 of .tuning forkrl9 so that a uniform spacingof the outgoing Vsignals is obtained.

With regard to the patented bias corrector Vabove referred to, the application of this bias 'Corrector'to'the present regenerating system can be carried out in almost'exactly the manner described in that patent for applying the bias cor- Y rector to a rotary regenerating system. It is merely necessary to insert in wires BCi and BCz the two operating windings of a four-winding relay BC (corresponding to relay Il of theabove mentioned patent) whose tongue will-close with its marking or spacing contact in accordance with whether the dot or dash contact of relay 2 is closed. Then an extra nfiarkingV contact may be applied to relay 26 (corresponding to the marking contact of relay il in the above mentioned patent) for the purpose of sendingV out a pulse of positive polarity each time a correction is made upon the fork. The eXtra marking contact of this relay 26 is then connected to the tongue of relay BC, and the marking and spacing contacts of this relay BC are connected through suitable locking windings of the relay itself to the automatic bias corrector magnets (designated 33 and 34 in the above mentioned patent). Since the correcting steps inra structure of the present system are closely analogous to those of the rotary regenerator system for which'theY above mentioned bias corrector was designed, this bias corrector willcoperate satis-V factorily without modification. The output current of the bias corrector can be applied to the polarized moving coil cable relay 2 exactly as illustrated and described in the above mentioned patent.

Although the preferred embodiment of the present invention is described and illustrated as f having a fork which runscfaster than the centerhole speed of the signalsand` is then corrected from time to time by retarding the fork, the converse arrangement can also be used in which the fork isV normally slow and the corrections serve to accelerateit. In all cases, however, it is preferred to correct only in one direction (retarding or accelerating) and to apply each correction at a predetermined strength for a predetermined length of time. Preferably the duration of each correction should be of the order of ve to fifteen center holes, since an unduly long correction period precludes the possibility of frequent corrections and an unduly short Vvperiod necessitates such a strong correction that the smooth vibration of the fork is disturbed. For signals of the rate ordinarily used` in submarine cables, it has been found advisable to adjust the strength and duration of each correction so as to set the fork back approximately'/go of a center hole in phase, and to make the fork speed exceed the signal speed by suchan amount that approximately 20 or 30 corrections per minute will take place.

What I claim is:

l. A signal regenerating telegraph repeater -V comprising an incoming relay, a vibratory tim- Ying device, a signal retransmitting' relay and connections for controlling the position' of said retransmitting rela;7 from said incoming relay and for Ycontrolling the exact time at which suchcposition shall become effective from said kvibratory timing device,V in combination withY corrector means for determining thefphase difference between the motions-of said incoming relay and said vibratory device and correcting means having a predetermined interval of operation, controlled by said corrector means vfor applying to Vsaid vibratory device a phase correction of xed amount. Y Y

2. A signal re-shaping Vtelegraph repeating between said timer and said receiving relay exceeding a certain value. Y

3. A telegraphic signal `regenerating system comprisingY a receiving relay, a vibratory timing member, a transmitting relay jointly controlled by'said'receiving relay and said vibratory member, together with a variable delay determining Y device, a corrector relay operated with'said receiving relay,` means for correcting the speed of Vthe fork in response to a difference in the time interval between the fork vibration and theoperation of the corrector relay differs in one predetermined sens'e from the-time interval deter- Ymined by said variable delay device and a second variable delaydevice, for determining the interval of operation'of said correcting means. y

4. -A' telegraphic signal regenerating system comprising'a receivingfrelay, a vibratory timing member, a transmitting relay jointly controlled by said receiving, relay and said vibratory member,rtogether wtha Variable delay determining device, correcting means operable only when the time-interval between the fork vibration and the operation-of the receiving relay differs in a given sense fromY the time interval determined by said variable delay'device, a second variable delay de- :termining device operative in responseto operation of said correcting means, a Vspeed changing magnet for said member and means responsive tothe operation of said. second variable delay determining deviceA for changing the speed of said vibratory member for an interval determined by said second variabledelay device.

` Y MARION H. WOODWARD. 

